Citrulline/malate promotes aerobic energy production in human exercising muscle.
Bendahan D, Mattei JP, Ghattas B, Confort-Gouny S, Le Guern ME, Cozzone PJ.
Centre de Resonance Magnetique Biologique et Medicale, UMR CNRS 6612, Faculte de Medecine de la Timone, 27 Boulevard Jean Moulin, 13005 Marseille, France.
BACKGROUND: Previous studies have shown an antiasthenic effect of citrulline/malate (CM) but the mechanism of action at the muscular level remains unknown. OBJECTIVE: To investigate the effects of CM supplementation on muscle energetics. METHODS: Eighteen men complaining of fatigue but with no documented disease were included in the study. A rest-exercise (finger flexions)-recovery protocol was performed twice before (D-7 and D0), three times during (D3, D8, D15), and once after (D22) 15 days of oral supplementation with 6 g/day CM. Metabolism of the flexor digitorum superficialis was analysed by (31)P magnetic resonance spectroscopy at 4.7 T. RESULTS: Metabolic variables measured twice before CM ingestion showed no differences, indicating good reproducibility of measurements and no learning effect from repeating the exercise protocol. CM ingestion resulted in a significant reduction in the sensation of fatigue, a 34% increase in the rate of oxidative ATP production during exercise, and a 20% increase in the rate of phosphocreatine recovery after exercise, indicating a larger contribution of oxidative ATP synthesis to energy production. Considering subjects individually and variables characterising aerobic function, extrema were measured after either eight or 15 days of treatment, indicating chronological heterogeneity of treatment induced changes. One way analysis of variance confirmed improved aerobic function, which may be the result of an enhanced malate supply activating ATP production from the tricarboxylic acid cycle through anaplerotic reactions. CONCLUSION: The changes in muscle metabolism produced by CM treatment indicate that CM may promote aerobic energy production.
PMID: 12145119 [PubMed - indexed for MEDLINE]
I’ve heard nothing but good things from this supp. Apparently it’s valuable for endurance. Thoughts?
do A search on this supp. I posted an article about it a year or two ago. It is good stuff IMo. It is a must for any runner. IF i were you i would just buy the pure cit malate from 1fast400.com The more you take the better the benefit.
I took Xtend for the 2nd time yesterday and I noticed quite a big difference in the weight room. I could throw up an extra set like it was nothing. Normally I pout and cry after doing a few sets of squats but I didn’t do that yesterday!! Who knows if it’s the BCAA’s or the Citrulline Malate. In total I consumed 2.5 grams of CM during my workout.
"Supplementing the diet with arginine has had limited success in increasing its levels and NO2 in tissues. Studies have shown that the rate of synthesis of arginine in the body is unaffected by intake of dietary arginine. One reason may be the short half-life (one hour) of dietary arginine. Also, dietary arginine is used mostly in the liver, where uptake of arginine is rapid after eating a meal containing about 30-50 grams of protein (about 1-2 grams of arginine). Instead, dietary supplementation with arginine’s precursor, citrulline, has been shown to be more efficient in increasing tissue arginine and NO2 levels. Therefore, citrulline serves as a substrate for energy precursors. "